1. Field of the Invention
Embodiments of the invention relate to high-voltage bushings in general, and in particular to high-voltage bushings for use in cryogenics applications involving superconducting devices.
2. Discussion of Related Art
Superconducting Fault Current Limiters (SCFCL) are a class of devices that operate at a cryogenic temperature and are often used in electrical transmission or distribution lines that are subjected to high voltages and high currents. SCFCLs are often used to provide protection against current surges, for example in power transmission networks.
Because SCFLs operate at cryogenic temperatures, large temperature differences are often experienced between the superconductive elements of the SCFL and the external equipment connected thereto. For example, cryogenic temperatures may be about −200 C, while the external equipment typically resides at ambient temperature. As such, a connection structure must be provided between the superconductive elements and the external equipment to accommodate the temperature transition, while also minimizing thermal losses.
Conventional high voltage bushings can fail when used at cryogenics temperature. The main failure mechanism is thermal stress due to the large temperature variations between ambient and cryogenic temperatures. Having a reliable high voltage bushing is important to the success of superconducting devices including SCFLs, transformers, generators, motors, energy storage devices and others. Thus, there is a need for an improved high voltage bushing for use in cryogenic applications.